This invention relates to the electrophotographic reproducing apparatus and more particularly to an exposure system therefor which includes means for moving the document past a stationary illumination exposure system.
One type of electrophotographic reproducing apparatus comprises a document transport belt which supports a document to be reproduced for movement past a stationary illumination source for flooding the document with light, which light is reflected in a predetermined pattern, in accordance with the image on the document to be reproduced. The light pattern impinges on a uniformly charged portion of a photoreceptor to effect discharge thereof whereby a latent electrostatic image is formed on the photoreceptor. The image is subsequently rendered visible through development with electroscopic marking particles commonly referred to as toner.
Another type of electrophotographic reproducing apparatus comprises a transparent platen for stationarily supporting a document to be reproduced, the document being flooded with illumination which is reflected as a light pattern along an optical path and impinges upon the photoreceptor. In this type of apparatus, the illumination source is moved relative to the document to thereby illuminate, in sequence, each portion of the document. In this manner, a light image is flowed on to the photoreceptor which is moved in synchronism with the movement of the illumination source. In order to prevent a dark border or edge being developed on the photoreceptor with subsequent transfer to the copy paper a diffuse reflector structure is normally provided behind the document and in contact therewith during document exposure. Portions of the reflector extend beyond the edges of the document and reflect illumination adjacent the edges of the document along the optical path and onto the photoreceptor to thereby discharge the photoreceptor adjacent the areas struck by the light pattern.
In an apparatus of the type herein contemplated, therefore, one having a stationary illumination source and means for moving a document therepast, the reflector would have to be spaced away from the document to permit the document to be moved relative to the illumination source. With such an arrangement the reflector irradiance, due to the spacing, is not adequate to prevent a dark border or edge appearing on the finished copy. Moreover, when the illumination has to pass through a document belt before it impinges on the reflector, the illumination is attenuated thereby adding to the problem of insufficient reflector irradiance.
It is the primary object of this invention to provide an improved imaging system for electrophotographic reproducing apparatus wherein the document is moved past a fixed exposure station.